Contact type image sensor

Abstract: A contactless image sensor comprises a light source (1,2) for irradiating the light onto an original, photoelectric converting elements for photoelectrically converting the light from the original (4), an image pickup device (7) for guiding the light from the original to the photoelectric converting elements (9), and a frame body (10) for holding them. The frame body includes a light transmitting portion (6) and a light non-transmitting portion and they are integrally pressing-out molded by plastics. Namely, the optical path portion (6) and the optical guide (3) of the frame body are made of transparent plastics and the other portions of the frame body are made of colored plastics having a light shielding performance.

Description: The present invention relates to a contact type image sensor according to the preamble of claim 1 and, more particularly, to a contact type image sensor having a frame body to hold a light source to irradiate a light onto an original, photoelectric converting elements for photoelectrically converting the light from the original, and a lens array for guiding the light from the original to an array of the photoelectric converting elements. Hitherto, as shown in a cross sectional view in Fig. 7, a conventional contact type image sensor is constructed in a manner such that a sensor array 8 corresponding to a length of an original to be read, a point light source array 1 in which a plurality of point light sources 2 for irradiating an original surface are arranged in a line on a board, an image pickup device array 7 to form an image of the light from the original onto a light receiving portion of photoelectric converting elements 9 on the sensor array 8, and a cover glass 11 to support the original are positioned and fixed to one frame body 10. As a point light source array 1, LED elements are generally used from a viewpoint of a low electric power consumption and a long life. The LED elements are attached in a line on a board made of a material such as glass epoxy or the like together with registers for current limitation by soldering or the like. However, in the above conventional contact type image sensor, there are the following problems. (1) That is, in the above conventional sensor, since the cover glass 11 and the frame body 10 are the individual parts, they become causes of an increase in costs because of the reasons such that the number of parts is large and a process for adhering the cover glass 11 to the frame body 10 in order to position and fix the cover glass is needed and the like. (2) It is difficult to completely eliminate a height difference between the cover glass 11 and the framing body 10 in terms of the precision. Therefore, in case of a reading apparatus of a sheet through type, in order to prevent that the original collides with the height different portion, it is necessary to take a countermeasure such that a Mylar sheet is adhered to the height different portion or the like, so that it also becomes a cause of an increase in costs. (3) There is also a technical subject as follows. A soldering ball at the time when the LED elements of the LED array are soldered or a foreign matter such as a board scrap from an LED board cut surface or the like adhered to the light source is moved onto an optical path of a rear surface of the cover glass 11, thereby light shielding or reflecting the light from the light source 2 onto an original reading line or the light from the original reading line to the image pickup device, so that erroneous information occurs for a sensor and appears as a black stripe or a white stripe in an output image. A generic contact type image sensor is known from EP-A-0 520 430. This sensor comprises a light source for irradiating an original with light. Photoelectric converting elements photoelectrically convert the light from the original. The light source and the photoelectric converting elements are accommodated in a frame body. The frame body includes a light transmission portion and a light non-transmission portion made of plastics by extruding. Further contact type image sensors are known from EP-A-0 508 709 and EP-A-0 554 825. It is an object of the present invention to further develop a contact type image sensor according to the preamble of claim 1 such that it can be produced at low costs. This object is achieved by the features of claim 1. Advantageous further developments are set out in the dependent claims. According to the invention, a part of the frame body for holding the light source, photoelectric converting elements, and lens array which are component elements of the contact type image sensor is used as an original supporting body, at least a part of the original supporting body is constructed by a light transmitting material, and the frame body is integrally extruded by plastics, so that the number of parts of the contact type image sensor is reduced and a height different portion between the original supporting body and the frame body is eliminated. Further, so long as an optical guide to guide the light of the light source to the original is integrally extruded by transparent plastics, the light source can be isolated, thereby making it possible to prevent that a foreign matter dropped out from the light source obstructs the optical axis. Fig. 1 is a perspective view showing an external view of a contact type image sensor according to an embodiment of the invention; Fig. 2 is a cross sectional view of a contact type image sensor according to an embodiment 1 of the invention; Fig. 3 is a cross sectional view of a contact type image sensor according to an embodiment 2 of the invention; Fig. 4 is a schematic diagram showing an example of a forming apparatus of a frame body which is used in the invention; Fig. 5 is a cross sectional view of the frame body; Fig. 6 is a schematic constructional diagram showing an example of a facsimile having a communicating function as an image information processing apparatus constructed by using the contact type image sensor of the invention; and Fig. 7 is a cross sectional view of a conventional contact type image sensor. Preferred embodiments of the invention will now be described hereinbelow. Fig. 1 is a perspective view showing an external view of a contact type image sensor according an embodiment of the invention. Reference numeral 10 denotes a frame body of the contact type image sensor. The frame body has a colored portion 10' and a transparent portion (window portion) 6. A sensor array as photoelectric converting elements is ordinarily arranged at a predetermined position of the frame body 10 and fixed. A light source, an optical guide, an image pickup device, and the like are arranged on the frame body 10 as necessary. According to the present invention, the frame body 10 is made of molded plastics (molded resin). Specific embodiments will now be described with reference to a cross sectional view which is seen from the same direction as that of a cross sectional view taken along the line II - II in Fig. 1. The embodiment of the invention will now be described in detail with reference to the drawings hereinbelow. Fig. 2 is a cross sectional view showing the first embodiment of a contact type image sensor of the invention. In the diagram, reference numeral 1 indicates an LED array as a light source to illuminate an original. The LED array is constructed by attaching a number of LED chips 2 in a line by soldering in correspondence to the original. Reference numeral 3 denotes an optical guide to effectively guide a light from the LED array 1 to a reading line 5 of an original 4; 6 the window portion (which is a part of the frame body 10) made of plastics having a light transmission performance; 7 the lens array as an image pickup device to form an image of optical information on the original surface; 8 the sensor array which is constructed by arranging the photoelectric converting elements 9 to convert the light information formed as an image by the lens array 7 to the electric signal in correspondence to the length of original to be read; and 10 the frame body to slide and insert the LED array 1, lens array 7, and sensor array 8 from the lateral direction (in the direction perpendicular to the paper surface), thereby positioning and fixing them. The frame body 10 including the window portion 6 and the optical guide 3 are integrally formed by a method of a extruding two-color molding using a plastics material. The window portion 6 and the optical guide 3 are made of a transparent plastics material and the other portions (hatched portions in the diagram) are made of a black plastics material which can easily absorb the light. Fig. 3 is a cross sectional view showing the second embodiment of a contact type image sensor of the invention. As shown in Fig. 3, in a manner similar to the first embodiment, the optical guide 3 and the window portion 6 are integrally extruding by using transparent plastics and the portions except the window porion 6 of the frame body 10 are integrally extruded by using black plastics. As a method of attaching the parts, the lens array 7 as an image pickup device is come into contact with the window portion 6 in the direction of an arrow from the side opposite to the window portion 6 of the frame body 10 and is fitted into the frame body 10. Further, the LED array 1 and the sensor array 8 are inserted into the frame body 10 from the lower side and are fixed in a manner similar to the above processes. The window portion 6 is narrowed like a tapered shape toward the original side in order to prevent that information of the portions other than the reading line 5 of the original 4 becomes a stray light and that it causes erroneous information of a sensor output. Since they are extruded, the optical guide 3 and the window portion 6 can be also easily integrally molded. A extrusion method for forming the frame body which is used in the invention will now be described. Fig. 4 is a schematic diagram showing an extruding apparatus. The frame body 10 as shown in Fig. 5 can be formed by such an apparatus. The apparatus is mainly constructed by four dies CA, CB, CC, and CD. The die CA has a cavity to mold the window portion 6 and the optical guide 3. An injector having a piston 21 and a cylinder (tank) 23 to inject transparent plastics is provided for the cavity. The die CB is adjacent to the die CA and has a cavity to mold the hatched portion 10' in Fig. 5. An injector including a piston 22 and cylinder (tank) 24 to inject colored plastics is provided for the cavity. The die CC is adjacent to the die CB and is used to adhere the transparent plastics serving as an optical guide 3 which was molded by the die CA and passed through the die CB to the colored portion 10' made of colored plastics. The die CD is adjacent to the die CC. In the die CD, the transparent plastics serving as a window portion 6 and the colored portion 10' are adhered. As mentioned above, the transparent plastics and the colored plastics are integrally extruded, thereby forming the frame body 10. The electric converting elements are inserted into a hollow portion 13 of the frame body 10, the image pickup device is inserted into a hollow portion 12, and the light source is inserted into a hollow portion 21. Both sides in the longitudinal direction of the frame body (the direction perpendicular to the paper surface), namely, the inserting surfaces to which the photoelectric converting elements, image pickup device, and light source are inserted are capped by side plates, so that the contact type image sensor is completed. As plastics which are used in the invention, a natural resin or a synthetic resin of an organic high molecular substance is used. Any one of the thermoplastic resin or the thermosetting resin can be used. Specifically speaking, polyvinyl chloride, polyethylene, polystyrene, polycarbonate, phenol resin, urea resin, epoxy resin, melamine resin, or the like can be used. It is particularly desirable to use polycarbonate from viewpoints of a mechanical intensity, easiness of coloring, a degree of transparency at the time of uncoloring, a stability of dimensions, and the like in the molded product. More preferably, a conductive material is mixed into the colored plastics, thereby providing a conductivity. In case of providing the conductivity, the frame body is held to a predetermined reference potential (for example, 0 potential), thereby making it possible to prevent a bad influence based on static electricities by the friction with the original. In the foregoing embodiments, the frame body is integrally formed by the extruding it with the apparatus in Fig. 4 by using transparent polycarbonate and polycarbonate containing a black pigment and conductive carbon. Fig. 6 is a schematic constructional diagram showing an example of a facsimile having a communicating function as an image information processing apparatus constructed by using the above contact type image sensor. In the diagram, reference numeral 102 denotes a feed roller as feeding means for feeding the original 4 toward the reading position; 104 a separating member for certainly separating and feeding the original 4 one by one; and 106 a platen roller as conveying means which is attached at the reading position for a sensor unit 100 and is used for restricting the surface of the original 4 to be read and for conveying the original 4. In the case where a frame body of the sensor unit 100 is conductive, the frame body is held at a predetermined potential by connecting with an earth potential of the apparatus. P indicates a recording medium having a shape like a roll paper in the example shown in the diagram. In case of image information read out by the sensor unit 100, a facsimile apparatus, or the like, the image information transmitted from the outside is reproduced on a recording paper which was taken out. Reference numeral 110 denotes a recording head as recording means for performing the image formation and various kinds of recording heads such as thermal head, inkjet recording head, and the like can be used. A serial type or a line type can be also used as a recording head. Reference numeral 112 denotes a platen roller as conveying means for conveying the recording medium P to the recording position by the recording head 110 and for restricting the surface to be recorded. Reference numeral 120 indicates an operation panel on which switches for accepting an operation input as input/output means, a display section for informing a message and a state of the apparatus, and the like are arranged. Reference numeral 130 denotes a system control board as control means on which a control section (controller) to control each section, a driving circuit (driver) of the photoelectric converting elements, a processing section (processor) of the image information, a transmitting and receiving section, and the like are provided. Reference numeral 140 denotes a power source of the apparatus. As recording means which is used in the information processing apparatus using the invention, it is preferable to use the recording means whose representative construction and principle have been disclosed in US-A-4 723 129 and US-A-4 740 796. The above system is effective because at least one driving signal which corresponds to the recording information and gives a rapid temperature increase exceeding a nuclear boiling is supplied to an electrothermal transducer arranged in correspondence to a sheet or a liquid path in which a liquid (ink) is held, thereby causing a thermal energy in the electrothermal transducer and causing a film boiling on the thermal operational surface of the recording head, so that a bubble in the liquid (ink) corresponding to the driving signal in a one-to-one corresponding relation. The liquid (ink) is discharged through an opening for discharge by growth or contraction of the bubble, thereby forming at least one liquid droplet. As a full-line type recording head having a length corresponding to a width of the maximum recording medium which can be recorded by the recording apparatus, either one of the construction which satisfies the length and the construction as one integrally formed recording head can be used by a combination of a plurality of recording heads as disclosed in the above specifications. In addition, the invention is also effective in case of using, the recording head of the exchangeable chip type in which the electrical connection with the apparatus main body or the supply of the ink from the apparatus main body can be performed by attaching the head to the apparatus main body or the cartridge type recording head in which an ink tank is integrally provided for the recording head itself. As mentioned above, according to the invention, by integrally extruding the frame body by plastics (preferably, the optical path portion of the frame body and the optical guide are molded by a transparent material and the other portions of the frame body are molded by a colored material having the light shielding performance by the integrally pressing-out molding method), (1) the conventional original supporting plate and frame body are integrally molded, so that the number of parts can be reduced and the costs can be also decreased; (2) the original supporting plate and the frame body are integrally molded, so that the height different portion between the conventional original supporting plate and frame body can be eliminated, and the Mylar sheet or the like to bury the height different portion for smoothly conveying the original is not needed; (3) by integrally molding the optical guide, the light of the light source can be efficiently guided to the original, the illuminance on the original surface can be raised, and the invention can be applied to a high speed and high resolution sensor; and since the light source is covered by the optical guide, it is possible to prevent that the foreign matter which is dropped out from the light source is moved onto the optical path and that it becomes erroneous information. A contactless image sensor comprises a light -source for irradiating the light onto an original, photoelectric converting elements for photoelectrically converting the light from the original, an image pickup device for guiding the light from the original to the photoelectric converting elements, and a frame body for holding them. The frame body includes a light transmitting portion and a light non-transmitting portion and they are integrally extruded by plastics. Namely, the optical path portion and the optical guide of the frame body are made of transparent plastics and the other portions of the frame body are made of colored plastics having a light shielding performance.

Claims: A contact type image sensor having a light source (1, 2) for irradiating an original (4) with light, photoelectric converting elements (9) for photoelectrically converting said light from said original (4), and a frame body (10) for holding said light source (1, 2) and said photoelectric converting elements (9), wherein said frame body (10) includes a light transmission portion (6) and a light non-transmission portion, said light non-transmission portion being made of plastics by extruding, characterized in that both said light transmission portion (6) and said light non-transmission portion are integrally formed by simultaneous extrusion. A sensor according to claim 1, characterized in that a part of said frame body (10) to hold said light source (1, 2) and a lens array (7) for guiding the light from the original (4) to said photoelectric converting elements (9) is used as an original supporting body. A sensor according to claim 2, characterized in that in said original supporting body, at least an optical path portion (3) in a range from said light source (1, 2) to a reading line (5) and an optical path portion in a range from said reading line (5) to said lens array (7) are made of transparent plastics, and the other portions of the frame body (10) except said transparent plastics portions of said original supporting body are made of colored plastics having a light shielding performance. A sensor according to claim 2, characterized in that, together with said frame body (10), an optical guide (3) for guiding the light of said light source (1, 2) to said original (4) is integrally extruded by plastics. A sensor according to claim 2, characterized in that an abrasion resistant coating process is performed onto at least the region of said reading line (5) on the surface of said original supporting body. A sensor according to claim 1, characterized in that said light transmission portion (6) and said light non-transmission portion exhibit no height difference therebetween at the side contacting the original. A sensor according to claim 1, characterized in that said frame body (10) including said light transmission portion (6) and said light non-transmission portion has a uniform-sectional area configuration in a longitudinal direction.

Inventors: TABATA MASAMI, TABATA, MASAMI, TABATA, MASAMI, C/O CANON K.K.
Applicants: CANON KK, CANON KABUSHIKI KAISHA
Application year: 1994
Main classification: H04N1
IPC codes: H04N1, B29D11